Experimental studies have shown that isolichenan is produced only when the two lichen components – fungus and alga – are growing together, not when grown separately.

[6] In 1947, Kurt Heinrich Meyer and P. Gürtler, discussing the preparation of lichenan, reported that the mother liquor contained a water-soluble glucan that could be purified by repeated freezing and thawing.

[13] Compared with, for example, amylose (a linear α-(1→4)-linked glucan and the major component of starch), isolichenan has a relatively weak iodine-staining reaction.

This weak staining intensity is thought to be a result of its preponderance of (1→3) linkages, a property that reduces the formation of the polyiodide-complex that gives the positive reaction its blue colour.

[9] The relatively short chain length of isolichenan may explain why it is soluble in cold water after it has been extracted from the lichen thallus.

[6] Similar to isolichenan, the α-D-glucan known as Ci-3 consists of 1→3 and 1→4 linked α-D-glucose residues in ratio of 2:1, but with a much higher degree of polymerization and a molecular weight of about 2000 kD.

[9] As the discrepancies in reported values demonstrate, lichens produce isolichenan-type polysaccharides with considerable variation in linkage ratios as well as molecular weight, even within the same species.

Parmeliaceae genera and species containing isolichenan include: Alectoria (A. sulcata, A. sarmentosa); Cetraria (Cetraria cucullata, C. islandica, C. nivaris, C. richardsonii; Evernia (E. prunastri); Letharia (L. vulpina); Neuropogon (N. aurantiaco-ater); Parmelia (P. caperata, P. cetrarioides, P. conspersa, P. hypotrypella, P. laevior, P. nikkoensis, P. saxatilis, P. tinctorum); Parmotrema (P. cetrarum, P. araucaria, P. sulcata); and Usnea (U. barbata, U. baylei, U. faciata, U. longissima, U. meridionalis, U. rubescens).

A few members of the family Ramalinaceae have been shown to contain isolichenan, including Ramalina celastri, R. ecklonii, R. scopulorum, and R. usnea.

[30] Isolichenan is synthesized by the mycobiont only in the presence of its symbiotic partner (the green alga Trebouxia) in a special microenvironment – the lichen thallus.

The triggering of this phenomenon and the biological function of isolichenan in the symbiotic relationship between fungi and algae is still unknown.